Many vehicles such as highway trucks include trailing arm type suspensions which support a rear axle and define its path of movement with respect to the vehicle frame. In some current highway truck designs, each trailing arm is constructed of spring steel and may comprise one or more “leaves.” The term “leaves” is used because at least some of the trailing arms being used by truck manufacturers are being made by leaf spring manufacturers from materials and in configurations that are or were used in “leaf” springs. In conventional designs of this type of suspensions, outboard ends of the axle are secured to respective trailing arms and, in effect, the arms support and locate the axle with respect to the vehicle frame.
In some current suspension designs, the leading end of the trailing arm is suspended below its associated frame member by a hanger bracket. These hanger brackets are typically rigid cast components, and substantially resist bending in response to torsional stresses placed on the bracket by the trailing arm. These brackets typically depend downwardly only a short distance with respect to the frame. As a result, the distance between the trailing arm pivot axis and ground can be substantial. The distance of the pivot axis above ground level can affect the ride quality of the vehicle. It is usually desirable to lower the pivot axis when possible. However, simply elongating an existing hanger bracket design in order to lower the trailing arm pivot axis, does not provide satisfactory performance.